Recording galvanometer



Sept. 10, 1929. 1 F. F..UEHL|NG 1,727,494

RECORDING 'GALVANOMETER Filed Jan. 27.11927 2 Sheets-Sheet 1 Patented sept. 1o, 1929.

PATENTA OFFICE.

FRITZ FREDERICK- UEHLING, OF YASSAIC, NEW JERSEY.

RECORDING GALVANOMETER.

Application filed Janualy 27, 1927. Serial No. 164,091.

My invention relates. to recording galvanometers or millivoltnieters, and embodies a novel method of transmitting the delicate mo- I tion of the galvanometer needle to a more rugged device for moving a pen or marker in proportion to changes in the reading of the galvanometer. Although my invention lends itself to any of the well known applications of the 'galvanometen I am confining this description to one particular form, namely, that of a recording pyrometer in which the electro-motive force of a thermo-couple is recorded by the recording galvanometer, the latter being calibrated in degrees of temperature instead of in'electrical units. My invention particularly relates to means for utilizing the delicate needle of a galvanorneter, as a contact member for definitely closing electricy circuits which control the recording device, 20.the latter being operated by an independent source .of power.

Figure 1 is a plan view' of the recording galvanometer, and special relays by which it is controlled, and with which it is electrically .25 connected.

Figure 2 is an enlarged plan view of the relays, a crosssection through the galvanometer or millivoltmeter along the line A-A of F igure 1, and a diagrammatical arrangement of different parts of the mechanism and their electrical connections.

' Figure 3 is an elevation of one of the relays, each of them being the same. Figures 4, 5, 6 and 7 show different positions of mercury switches, hereinafter referred to as connectors.

The same numerals referto the same parts in all of the illustrations. A galvanometer or millivoltmeter is permanently fastened to a worm wheel 1, Figure `1, so that the axis of the pivoted coil or armature of the galvanometer, coincides witlrthe axis of said "wheel. The galvanometer consists ofv the. usual permanent magnet 2, between the north andi-south poles of which, a v coil or armature 3 is pivoted at 4 and 5, Figure 2. r1Ehe electric current which tends to cause the coil `3 to rotate, passes throughan insulatedstud 6, a hair spring 7, pivoted coil 3,

5 0 hair spring- 8 and insulated stud 9. The reactionary force which determines the position of the pivoted coil` 3 and the needle 10 which 1s fastened to it, is caused by the hair springs 7 4and 8. These elements thus constitute a well known form of galvanometer or millivoltmeter, the pivoted'coil 3 and needle 10, tending to turn through a definite angle depending upon the magnitude of the electric currentpassing through the coil 3 inthe manner stated.

In this particular application of my invention, the magnitude of the electric current which is measured by the needle 10 of the galvanometer, depends upon the temperature of a thermo-couple 11, the principle of which is we ll known and understood, said thermo-couple being placedin a medium, the temperature of which is to be recorded. The current thus created by the temperature-ofv the thernio-couple passes through wire 12, binding post 13, and a flexible connection 14, Figures 1 and 2, thence through hair spring 7 and pivoted coil .3, Figure 2, thence through hair spring 8, flexible connection 15, a resistance 17, and wire 19 back to the couple 11, Figures 1 and 2. The resistance 17, which is held in position by binding posts 16 and 18, is a very important feature of my invention and will be referred to later. v

rl`he galvanometer,consisting-'of the different parts above mentioned, is fastened to the worm wheel 1. Figures 1 and 2, by means of a bracket 20, Figure 2. Wheel 1 is rotatably mounted on'a stud 21, Figure 2, which stud is permanently fastened to the base 22. The worm wheell meshes with a worm 23, Figures 1 and 2, and is in geared connection with a reversible motor24 through shaft 25, worm wheel 26, worm 27, and shaft 28. The shaft 28 which extends from the motor andcarries worm 27, is supported by a bearing 29, While the shaft 25`which carries worm 23 and worm wheel 26, the latter meshing withworm 27 is supported by bearings 30 and 3.1, Figure, 1. It thus follows that as the'motor 24 rotates in one direction, wheel 1 including the galvanometer and its needle 10',will also rotate in one direction, but at a very much reduced velocity, due to the reduction gear already described. Likewise when the motor 24 rotates in the opposite direction, wheel 1 including the galvanometer 'and its needle 1() will 'also rotate in the opposite direction.

The motor 24 is operated by relays 35 and 36, Fig-ure 1, one of which closes the circuit which operates the motor in one direction, and they other of which closes the circuit which operates the motor in the opposite direction.

These relays are respectively actuated by a circuit which is closed when contact piece 32 at the end of needle'l() touches a contact disc 34, Figure 1.` and a circuit which is closed ary.

The circuits which actuate the relays, andv those which operate the motor in one direction or the other, also the novel manner in which unfailing contact is made between the delicate needle 10 of the' galvanometer, and the discs 33 or 34, will'be presently described in complete detail.

The thermo-couple 11 is so connected with the galvanometer that an `increase in its temperature will cause the needle 10 to rotate in the directionI which will establish contact between contact piece 32 and disc 33. The circuit whichlis thus closed through the Contact disc 33' will actuate the relay 36, which relay will close the circuit through the motor24 to turn the wheel 1 and the galvanometer in aclockwise direction. This motion of wheel 1 in a clockwise direction will continue until the contact piece 32 has freed itself from the contact disc 33, at which time the relay will cease to ac t and the motor will'stop. Complete details of the relays 35 and 3G will be presently described. Should the temperature of the thermo-couple 11 increase still further, then the contact piece 32 will again touch the contact disc 33, thus again actuating the relay 36.which -operates the motor-to turn v the wheel 1 andgalvanometer still further in a clockwise-direction until the contact piece 32 has again freed itself from the contact disc 33, when the relay willcease to lact and the motor will stop. y

Likewise should the temperature of the thermo-'couple 11 drop, then the needle 10 including the contactpiece 32 will turn in a clockwise direct-ion,- thus making contact between contact piecev 32 and contact disc 34. The circuit which is thus closed through the contact disc 34, will. actuate the relay 35, which relay will--close the circuitthroughthe motor 24 to rotate the wheel 1 and galvanometer in la counter-clockwise direction. The

motion of the wheel 1 in a counter-clockwise direction will continue until the contact piece 32 has freed itself from the contact disc 34, at which time the motor will stop. Should thc temperature of the thermo-couple continue to drop. the contact piece 32 will again touch the contact disc 34, the wheel 1 and galvanometer will continue to rotate in a counterclockwise direction, until the Contact piece 32 has again freed itself from the disc 34. It is thus obvious that the wheel 1 will change its position in definite proportion to the temperature measured by the thermocouple.

The circuits which include the motor 24, and which cause it to operate in one direction or the other, are illustrated in dot and dash lines, and are respectively closed by the special relays 35 and 36. The circuits which actuate the relays, are illustrated in dotted lines, the circuit which actuates relay 35 being closed when the contact piece 32 touches contact dise 34, and the circuit which actuates the relay 35 being closed when the contact piece 32 touches contact disc 33.

A. very novel and important part of' this invention, is the method which I use in assuring definite contact between the contact piece 32 of the delicate needle 10 of the galvanometer` and the respective Contact disc 33 or 34. This consists of a clock or motor 41, Figure 1, or any other means for imparting motion'to the contact discs 33 and 34, and an -electrical resistance 17 which is included in both the circuit through the respective discs 33 and 34, andin the circuit passingthrough the galvanometer, which latter circuit 1n this particular form-of my invention includes the thermocoupl'e 11. The manner in which the resistance 17 functions will be presently described. rlhe clock 41 which rotates the contact discs 33 and'34, is supported by a. bracket 42 which is fastened to the base 22 by screws as illustrated. The clock drives the discs 33 and 34 through shaft 43 which is carried by bearings 44 and 45. The contact discs' 33 and'34 are insulated from each other by insulation 46 and from the Clock by insulation 47. n

In each of the relays 35 and 36 are utilized three mercurial connectors 48, 49, vand 50 and 48, 49a and 50a, respectively. These connectors are shown in-detail, and in different positions by Figures 4, 5, 6 and 7. Each connector consists of a hermetically sealed glass bulb 51 containing mercury. Into one end of each bulb is sealed a wire v52 which extends `into the bulb as illustrated, and protrudes to the outside of the bulb to permit making an electrical connection. Into the other end of protrudes to the outside to permit making it is' obvious that as the bulb is tilted in .a l

f/if the connector is tilted in a counter-clockelectrical connections. Each connectoris provided with a pocket, or well 54, into which extends vthe wire 53.` Each bulb contains a globulefof mercury 55, Figures 5 and 6. When/the bulb is so placed that the' pocket 54 is yon the right hand side, Figures 4 and 5,

clockwise direction, Figure f5, electric connections will be made through the mercury between the wires 52 and 53.- On the other hand wise direction,l Figure 4, the mercuryk will break into two globules, some of it remaining in the pocket 54, thus breaking electric connections between wires 52 and 53. Likewise ifthe connector is so placed that the pocket 54is on the left hand side, Figures 6 and 7, it is obvious that as the connector is tilted in a counter-clockwise direction, Figure 7, electric connection will be made through the mercury between wires 52 and 53, and as the connector Ais tilted in a clockwise direction, Figure 6, electric connection will be broken between wires 52 and 53. 25l

Connectors 48, 49, and 50, and connectors 48a, 492L and 50a of the relays 35 and 36 respectively, are mounted on tiltable blocks 56 and 56, which are respectively pivoted on bearings 57 and 58, and' bearingsl 59 and 60.v These bearings are fastened to base 61, and

to base 62, of the respective relays. A pair of stationary electro-magnets 63 are fastened to the base 6l of relay 35 by means of a bracket 64, and a pair of stationary electro-magnets 65 are fastened to the base 62 of relay 36 by means of a bracket 66. The purposeof magnets 63 are to attract a soft iron armature 67 which is screwed fast to the tiltable block 56 as illustrated. The armature 67 and the tiltable block towhich it is fastened are held in their normal position by a spring 68, the

' tension of which is adjustable by means of screw 69. The armature 67 and the tiltable block 56 to which it is fastened, are limited in motion by the adjusting screw 7 (l, which determines how far away from the magnets 63, v.the armature 67 may be pulled by the spring 68. Furthermore the distance which the magnets 63 may move armature 67 against the tension of the spring 68, is limited by the r adjusting screw 71. The adjusting screws 69 and 70 are threaded through a stationary bracket 72 which' is screwed fast to the base 61. The adjusting screw 71 is threaded through bracket 64 which supports the mag-` nets 63, and which bracket, as already stated,

. is also screwed fast to `the base 61. It is obvious from the above that, when -the magnets 63 are energized, they will attract the armature 67, thus causing the block 56, including the connectors 48, 49 andvr50, to tilt in one direction. and when the magnets 63 are deenergized, the spring 68 will cause them to tiltin the opposite direction.

The construction of relay.36 is exactly the same as that of relay 35, so that whcnmagnets are energized they will causetheblock 56, including the connectors 483,49a and 50a, to tilt in one direction, and when the magnet 65 are deenergized, the spring 73 will cause them to tilt in the opposite direction.

The connectors 48 andv49 of relay 35 are included in the circuit which operates the fno-- tor 24`to turn wheel'l and galvanometer 2 in a counter-clockwise direction. .They-are fastened to the tiltable block 56 by means of a clip 74, and are so placed on the tiltable block 56 that, when they are tilted by magnets 63, they will assume the position illustrated in Figure 7, thus making electrical connections 'in each 4of them; and when they are brought back to their normal position .by the spring 68 .they will assume lthe position illustrated'in Figure 6, thus breaking electrical connection 1n each of them. The connector 50 is fastened to the tiltable block 56 by means of clip 7 5,

and is included in the same circuit which position illustrated in Figure 5, thus making' electr-ical connections.

It thusfollows that when contact is made between contact piece 32 and contact disc 34, magnets 63 will become energized and tilt the block 56 with its break the circuit through the'magnets 63, and permit the spring 68 toY pull the tiltable block 56, with its connectors, back to the normal position in which, asalready stated, electrical A.connections through connector 50 i-s' again established. If electrical contact still exists between Contact piece 32 and disc 34, this cycle will repeat itself. In other words', so long as the circuit through contact piece 32 and disc `34 is closed, so long will the tiltable block to oscillate. This oscillation causesan interconnectors 48, 49 and 50. The tilting of connector 50 by the action of magnets 63, will 56, with its connectors 48, 49 and 50, continue mittent closing and opening of the circuit through connectors V48 and 49, which will operate the motor 24 to turn the wheelA l in acounter-clockwise direction, until contact b etween contact piece 32 and disc 34 is broken. When this happens the magnets 63, which are includedin the circuit through disc 34,

will-cease to function, and the connectors of relay 35 will assume theirnormal position by the action of the spring 68. In this position, as already stated, the circuit' through connectors 48 and 49 will be broken. thus causing the motor which has been turning the gal- Vanometer in a counter-clockwise direction to stop. y l

Likewise connectors 48 and 49 of relay 36 are included in the circuit which operates the motor 24 to turn wheel l and galvanometer 2 in a clockwise direction. They are fastened `to the tiltable block 56 by means of a clip 76, and are so placed that when they are tilted by magnets 65 they will assume the position illustrated in Figure 7, thus making electrical connection through each-of them;

and when they are brought back to their normal position by the spring 73, they will assume the position illustrated inFigure 6, thus breaking electrical connection through each of them. The connector is fastened to the tiltable block 56 by means of clip 77, and is included in the same circuit which includes magnets 65, and which is closed when contact is made between contact piece 32 of the galvanometer needle 10, and contact disc 33. The connector 50 is so placed on the tiltable block 56 that, when it is tilted by the magnets 65, it will assume the position illustrated in Figure 4, thus breaking electrical connection; and when it is broughtback to its normal position by the spring 73, it will assume the position illustrated in Figure 5, thus making electrical connection. It thus follows that,

when contact is made between contact piece 32 and disc 33, magnets will become energized and tilt the block 56 with its connectors 48, 49 and 50a. The tilting of connector 50 by the action of magnets 65 will break the circuit through said magnets and permit the spring 73 to pull the tiltable block 56, with its connectors, back to the-normal position in which electrical connectionthrough connector 50 is again established. If electrical contact still exists between contact piece 32 and disc 33, this cycle will repeat itself. In other words, so long as electrical contact exists between contact piece 32 and disc 33, so long will the tiltable block 56 with its connectors 48, 49 and 50 continue to oscillate. This oscillation` causes an intermittent closing and opening of the circuit through connectors 48 and 49, which will operate the motor 24 to turn the wheel 1 in a clockwise direction until contact between contact piece 32 and disc 33 is broken. Then thishappens, the magnets 65 which are included in the circuit through disc 33 will cease to function and the connectors of relay 36 will assume their normal posi- -tion by the action of the spring 73. In this position, as already stated, the circuit through connectors 48 and 49 will be broken, thus lcausing the motor which has been turning the galvanometer in a clockwise direction to stop.-

It will be noted from the above that the purpose of the connectors 48 and 49, and 48 and 49 respectively, Figure 2, is' to close the proper circuits for operating the motor 24, Figure 1, to turn the wheel 1, on which the galvanometer is mounted, in a counter-clockwlse, or clockwise, direction depending upon which ofthe magnets 63 or 65 areenergized.

The motor 24, as previously stated, is series wound, so that its direction of operation may be reverse'dby reversing the direction of the current through its armature without changing the direction of the current through its field. The field 78, and the armature 79 with its brushes 80 and 81, all of motor 24, are diagrammatically illustrated in Figure 2. When the circuit through connectors 48 and 49 has been closed by the action of niagnets 63, in the manner already stated, then the circuit which operates the motor to turn the galvanometer in counter-clockwise direction, starts at battery 82 Figure 2, passes through wires 83 and 84 to binding post 85, thence through flexible connection 86, connector 49, and iiexible connection 87 to binding post 88, thence through wire 89, through brush 81, armature 79, and brush 80 of the motor, thence through wires 90 and 91 to binding post 92, from binding post 92 v through fiexible connection 93, connector 48, and flexible connection 94 to binding post 95, thence through wires 96, 97, and the field 78 of the motor, back to the battery.

Likewise when the circuit through connectors 48 and 49 has been closed-by the ac- `tion of magnets 65, in the manner already stated, then the circuit which operates the motor to turn the galvanometer in a clockwise direction starts at battery 8,2, passes through wires 83 and 98 to binding post 99, thence through iexible connection 100, connector 48, and flexible connection 101 to binding post 102, from binding post 102 through \\'..cs 103 and 90, thence through brush 80,- armatures 79 and brush 81 of the motor, from brush 81 through wires 89 and 104 to binding post 105, from binding post 105 through flexible connection 106, connector 49, and iexibleconnection 107 to binding post 108, and thence through wires 109, 97, and the field 78 back to the battery. In order to facilitate the tracing of the circuits just described, the one which includes connectors 48 and 49 and which is closed when magnets 63 are energized, follows the straight line arrows, while the circuit which includes connectors 48 and 49, and is closed when magnets 65 are energized, follows the wavy line arrows.

lli

The circuits which energize magnets 63 tery 37, passes through wire 40 to magnets 63, from niagnets63 through wire 110 to binding post 111, from binding post A111 vthrough flexible connection 112, connector 50,

and fiexible connection 113 to binding post 114, from binding post 114 through wire 39 to bearing 44, and contactdisc 34, Figure 1, and thence, when Contact piece 32 touches contact disc 34, to needle 10, from needle 10 through hair spring 8,' stud 9 and liexible connection 15'to binding post 16, Figure 2, from binding post V16 through resistance 17 to binding post 18, and thence back to the battery through wire 38.

Likewise the circuit which includes mag' nets 65 starts at battery.115, passes through wire- 116 to magnets 65, from magnets 65 through wire 4117 to binding post 118, from binding post 118 through flexible connection 119, connector 50n and flexible connection 120 to 4binding post 121,-fro1n binding post 121 through wire 122, bearing 45, and contact disc 33, Figure 1, and thence, when contact piece 32 touches contact. disc 33, to needle 10, from needle 1() through hair spring 8, stud 9, and flexible connection 15'to binding post l 63I and battery 37 is closed-by contact between A 32 and 34, and to cause a current to flow in f vanometer in one direction or the other, de-

the opposite direction through the resistance 17 when the circuit which includes magnets 65 and battery 115 isclosed by Contact be tween 32 and 33 Figure 2. It is obvious that any current passing through the resistance 17 will cause a drop in potential across the resistance, which drop, or difference in potential between binding posts 16 and 18, will in turn cause a current to llow through the galpending upon the direction of the How of current through the resistance. ln other words, when there is a flow through needle 10,

hair spring 8, flexible connection 15, resistance 17 and wire 38, Figures 1 and 2, there will be a difference in potential between the binding posts 16 and 18 due to the dropv across the resistance 17 which will cause a flow from resistance 17, through wire 19, thermocouple 11, wire 12, flexible connection 14,

. pivoted coil 3, and flexible connection 15, back to the resistance 17.

- It thus'follows that the slightest pressure of contact piece 32 against theV slowly rotating discl 33, as caused bytheelectro-motive force of the thermo-,couple 11, will cause some current `to flow through the circuit which includes needle 10, flexible connection 15, resisttance 17 battery 115 'and magnets 65 of relay 36. The polarity of battery 115 is such that the drop across the resistance 17 will cause a flow through the thermo-couple and galvanometer, in the proper direction, to increase the turning moment of the pivoted coil 3, beyond that established by the temperature of the thermo-couple, Figure 2, thus increasing the pressure of the rubbing contact between contact piece 32 andl the slowly rotating disc 33. As the contact pressure be-A tween 32 and 33 increases, in the manner above stated, the flow through resistance 17 andinagnets 65 will also increase, thus still further increasing the drop through resistance `17. rlhis increased drop across resistance 17 will obviously also increase the flow through the thermo-couple and galvanometer so that contact piece 32 will be forced sti-ll tighter against disc 33. The pressure 'between the Contact piece 32 and the rotating disc 33, thus builds up until sulcient Contact force has been established to actuate the relay 35. As previously stated, with each oscillation of the relay 36, the circuit through magnets 65 and disc 33 will be broken in the connector 50a, thus permitting the needle 10 to adjust itself to the position determined by the effect of the thermo-couple alone. If, in this position, the contact piece 32 still touches disc 33, the above described action will repeat itself until the motor 24`has turned the galvanometer and needle 10 sufficiently in a counter-clockwise direction to entirely free the contact piece 32 from disc 33.

Likewise, theslighest pressure of contact piece 32 against the slowlyrotating disc 34, as caused by a drop in the electro-motive force of the thermo-couple 11, will cause some .current to flow through the circuit which includes needle 10, flexible connection 15, re-y sistance 17, battery 37 and magnets 63 of relay 35. rllhe polarity of battery 37 is such that the drop across the resistance 17 will cause a How through the thermo-couple and galvanometer in the proper direction to increase the turning moment of the pivoted coil 3, bee yond that established by the temperature of the Jthermo-couple, Figure 2, thus increasing the pressure of the rubbing contact between contact piece 32 and the rotating disc 34. As .the contact pressure between 32 and 34 increases, in the manner above stated, the tlow through resistance 17 and magnets 63 will also increase, thus still further increasing the drop through resistance 17. This increased drop across resistance 17 will obviously also increase the flow through the thermo-couple and galvanometer, so that contact piece 32 will be forced still tighter against disc 34. The pressure between the contact piece 32 and the rotating disc 34, thus builds up until sufficient contact force has been established to pass enough current to a'ctuate thc relay rection to entirely free the contact piece 32 from the disc 34.

It thus follows that the vslightest electrical contact between contact piece 32 and either of the contact discs 34 or 33, as may be caused by changes in the temperature of the couple 11, will be sufficiently augmented by the action of resistance 17, to insure the operation changes its position in proportion to changes .proper resistance to in the temperature of the couple 11, all in the manner described, the chart 127 may be calibrated in suitable units to provide a continuous and permanent record of the temperature changes.

Although I have illustrated the 'resistance 17 in a definite position, it is obvious that it may be located 1n different parts of the eircuits referred to. For example, resistance 17 may be located anywliere-between the junc tion of the wires 38 and-19, and the point at which they connect with the lpivoted coil 3, Figure 2. Furthermore, the hair spring 8, if properly designed, may in itself have the produce the required rex4 sults.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In a recording galvanoineter, the combination with a permanent magnet, of a coil pivoted between the north and south pole pieces ofthe magnet, a hair spring for resisting the motion of the pivoted coil, an indicating needle fastened to the coil, a contact,

piece with which the needle makes electrical contact when reflected to a given position, a circuit which includes the pivoted coil and the hair spring, and a circuit which includes the hair spring, the needle, and -the contact piece. l

2. In a device of the class described, the combination with an electrical resistance, of a galvanometer withv an indicatingneedle, said galvanometer being shunted across the resistance, an electric contactO piece in the path of the needle, and a circuit which includes the resistance, the needle and the con- 4. In a device of the class described, the combination with'a galvanoineter having an indicating needle, of. an electrical resistance,

combination with a reversible motor, of aciicuit which operates the motor in one direction, a second circuit which operates the motor in the opposite direction, a' relay which closes the fiist circuit, a second relay which closes the second circuit, a galvanoincter, an electrical resistance, a third circuit which iiicludes the galvanoiiieter and the electrical resistance, a fourth circuit whiehincludes c i `r esistance, a second electric circuit which includes vthe second contact disc, the needle and the resistance, and a third circuit which j includes the galvanomcter and the resistance.

7. In a device of the class described, the combination with a galvanometcr having an indicating needle, of a. switch, a motor, a circuit for operating the motor in one direction which includes theswitch, a second switch,

a second circuit for operating the motor in the opposite direction which includes the second switch` an electrical means for 'closing the first switch, a second electrical means for closing the second switch, a contact disc with which the needle of the galvanonieter collides when deiiectcd in one direction, a third circuit which includes the first electrical means, the needle and the contact disc, a seq/d ond Contact disc with which the needle of the galvanoineter eollides when deflected in the opposite direction, a fourth circuit which includes the second electrical means,- the needle and the second contact piece, an electrical resistance which is included in both the third and fourth circuits, and a fifth circuit which includes the resistance and the galvanoineter.

8. In a device of the class described, the combination with a .rotatably mounted galvanometer having an indicating needle, of aswitch, a motor, a circuit for operating the motor in one direction which 'includes the switch, a second switch, a second circuit for operating the motor in the-opposite direction which includes the second switch, electrical means for closing the lirstswitch, a second' electrical means for closing the second switch, a contact piecev withwhichthe needle of the galvanometer collides when deflected in one direction, a third circuit which includes the f irst electrical means, the needle and the contact piece, a second contact piece with which the needle 'collides when deflected in the opposite direction, a fourth circuit which included thesecond electrical means, the needle and the second contact' piece, an electrical resistance which is included in both the third and fourth circuits, a fifth circuit which includes the resistance and the galvanometer,

. and a geared connectionbetween the motor the resistance.

10. In a device of the class described, the

combination with a rotatably mounted galvanometer-having 'an indicating` needle, of electrical means for rotating the galvanometer in one direction, electrical means for rotating the galvanometer inthe oiipositedirection, a contact piece for making electrical contact with the needle when the needle is defiected in one direction, a second contact pieceifor making electrical contact with the needle when the needle is deflected in the opposite direction, an electrical .resistance, an electric circuit which includes the first rotating means, the resistance, the needle, and the first contact piece, a second electric circuit which includes the second rotating means, the resistance, the needle, 'and the second contact piece, automatic means for consecutively opening and closing the first circuit when the needle is in contact with the first contact piece), automatic means for consecutively opening' and closing the second circuit when the needle is in contact .with the second contact piece, and a thirdelectric circuit which includes the resistance and the galvanonieter.

Il In a device of the class described, the

y combination with a rotatably mounted galvanometer having. an indicating needle, of

electrical means for rotating Ythe galvaV no meterin one" direction, electrical means for rotating the galvanometer in the opposite direction, a relay for actuating the first rotating means, said relay comprising a connector, an electro-magnet for tilting the con` nector in one direction and a spring for tilting the connector in the opposite direction, a second relay for actuating the the second i'otating means, said second relay comprising a second connector, a second electro-magnet for tilting the second connector in one direction and a spring for tilting the second connector in the opposite direction, a, contact piece for making electrical Contact with the needle when the needle is deflected in one direction, a second contact piece for making electrical contact with the needle when the needle is defiected in the opposite direction, an electrical resistance, an electric circuitwhich includes the resistance, the needle, the first contact piece, the first connector and the first magnet. a second electric circuit which includes the resistance, theneedle, the second Contact piece, the secondconnector and the second magnet, and a third circuit which includes the resistance and the galvanoineter. l2. In a device of the class described, the combination with a galvanometer having an indicating needle, a contact piece with which the needle makes electrical contact when deflected to a given position, an electrical resistance, an electric circuit'whicli includes the galvanonieter and the resistance, and a second electric circuit which includes the needle, the centact piece, and the resistance.

13. In a device of the class described.l the combination with a galvanometer having an indicating needle, of an electrical resistance, a contact piece with which the needle collides when deflected in one direction, a second contactipiece with which the needle collides when deflected in the opposite direction, a circuit whicliincludes the galvanometer and the resistance, a battery, a second circuit which includes the battery, the resistance, the needle 'and the first contact piece, a second battery, and a third circuit which includes the second battery, the resistance, the needle and the second contact piece. Y

14. In a device of the class described, the combination with a galvanometer having an indicating needle, of a switch, an electromagnet for opening the switch, an electric circuit'for energizing the magnet which circuit includes the switch, automatic means for,

closing the switch when the magnet is deenergized, a second switch, a second electromagnet for opening the second switch, a second circuit for energizing the second magnet which circuit includes the second switch, automatic means for closing the second switch when the second magnet is deenergized, an electrical resistance which is included in both of the circuits, a contact piece for making electrical contact between itself and the needle to close the first circuit, a s econd contact piece for making electrical contact between itself and the needle to close the second circuit, and a third circuit which includes the resistance, and the galvanometer.

l5. A method for preventing adhe. ion between a delicately pivoted needle such as the needle of a galvanometer and an electrical contact piece when such a needle is used to closea circuit between itself and the contact piece, said method consisting in moving the contact piece by means of a clock or any other motive means in a planeV approximately at right angles to the plane in which the needle moves, vthus providing a rubbing effect between the needle and contact piece when they touch each other.

16. In a device of the class described, the combination with a tiltably mounted frame, of an electronlagnet for tilting the frame in one direction, automatic means for tilting the frame in the opposite direction when theinagnet is deenergized, a mercurial switch fastened to the tiltable frame, said switch being open when the frame has been tilted by the magnet and closed when `tilted by the automatic means, a second mercurial switch fastened to the tiltable frame, a third mercurial switch fastened to the tiltable frame, said second and third switches being closed when the frame'has been tilted by the magnetand open when tilted by the automatic means, a second tiltably mounted frame, a second electro-magnet for tilting the frame in one direction, automatic means for tilting the scc-ond frame in the opposite direction when the magnet is deenergized, a fourth mercury switch fastened to the second tiltable frame, said fourth switch being open when the second frame has been tilted by the magnet and closed when tilted by 4the automatic means, a fifth mercury switch fastened to the second frame, a sixth mercury switch fastened to the second frame, said fifth and sixth switches' being closed when the frame has been tilted by the magnetl and open when tilted by the automatic means, a pivoted needle actuated by an independent force, a contact piece with which the needle makes contact when it turns in one direction, a second contact piece with which the needle makes contact when it turns in the opposite direction, an electric circuit which includes the needle, the first contact piece, the first-switch and the first magnet,I a second electric circuit which includes the needle, the second contact piece, the fourth switch and the second magnet, a mo,-

- tora third electric circuit for operating-the motor in one direction said third circuit including the second and third mercury switches,`and a fourth circuit for operating the motor in opposite direction said fourth circuit including the fifth and sixth mercury switches.

17. In a device of the class described, the combination with a tiltably mounted frame, of an electromagn t for tilting the frame in one directioneautomatic means for tilting the frame in the opposite direction when the magnet is deenergized, a mercurial switch fastened to the tiltable frame, said switch being open when thel frame has been tilted by the magnet and closed when tilted by the automatic means, a second mercurial switch fastened to the tiltable frame, a third mercurial switch fastened to the tiltable frame, said second and third switches being closed when the frame has been tilted by the magnet and open when tilted by the automatic means, a second tiltably mounted frame, a second electro-magnet for tilting the frame in one drection, autolnatic means for tiltingthe sec' ond frame in the opposite direction when the magnet is deenergized, a fourth mercury switch fastened to the second tiltable frame, said fourth switch being open when the second frame has been tilted by the magnet and closed when tilted b the automatic means, a fifth mercury switc fastened to the second frame, a sixth mercury switch fastened to the second frame, said fifth and sixth switches being closed when the frame has'been tilted by the magnet andopen when tilted.4 by the automatic means, a pivoted needle actuated by an independent force, a contact piece with which the needle makes contact when it turns in one direction, a second contact piece' with which the needle makes contact when it turns in theopposite direction, an electric circuit which includes the needle, the first contact piece, the first switch and the first magnet, a second electric circuit which includes the needle, the second contact piece, the fourth switch and the second magnet, .a motor, a third electric cireuitfor operating the mo-f tor in one direction said third circuit includ-. ing the second and third mercury switches, a fourth circuit for operating the motor in opposite direction said fourth circuit including the fifth and sixth mercury switches,a rotatably mounted support for carrying the pivoted needle, and a geared connection' between the motor and the support.

FRITZ FREDERICK UEHLING. 

